Application for KAGRA (LCGT) Application for KAGRA (LCGT) MembershipMembership

Jun Xu, Jingya Wang, Lihe Zheng, Huili TangJun Xu, Jingya Wang, Lihe Zheng, Huili Tang Shanghai Institute of Ceramics, Chinese Academy of SciencesShanghai Institute of Ceramics, Chinese Academy of Sciences

The KAGRA (LCGT) Face-To-Face Meeting, ICRRThe KAGRA (LCGT) Face-To-Face Meeting, ICRRFeb 2-4, 2012Feb 2-4, 2012

Applicants

• Jun Xu: Group Leader• Jingya Wang: Machining Research• Lihe Zheng: Measurement Research• Huili Tang: Crystal Growth Research

OutlineOutlineI.I. BackgroundBackgroundII.II. MotivationMotivationIII.III. Proposed WorksProposed Works

1.1. Large-Size Sapphire Crystal GrowthLarge-Size Sapphire Crystal Growth2.2. Detection & Machining of Large-Size Sapphire Detection & Machining of Large-Size Sapphire

CrystalCrystalIV.IV. FacilityFacilityV.V. Human ResourcesHuman ResourcesVI.VI. SummarySummary

I. Background: Core optics of I. Background: Core optics of KAGRAKAGRAf2f meeting, 3 Feb. 2012, Norikatsu Mio, University of Tokyof2f meeting, 3 Feb. 2012, Norikatsu Mio, University of Tokyo

Laser MC1

MC2

MC3 PRM PR2

PR3BS

SR3

SR2

SRM

ITMX

ITMY

ETMX

ETMY

MT1

MT2

Large-diameter mirrors

38cm

10cm Mirrors for Main cavitiesMirrors for Main cavitiesInitial: SilicaInitial: Silica

Final: SapphireFinal: Sapphire

I. Background: Requirements for Sapphire I. Background: Requirements for Sapphire CrystalCrystalSHNU-LCGT Round Table Meeting, 19 Aug. 2011, Takaaki KajitaSHNU-LCGT Round Table Meeting, 19 Aug. 2011, Takaaki Kajita

II. Center Activities and II. Center Activities and MotivationMotivation

1. Sapphire crystal research center located in SIC, CAS was founded in July, 2010, aiming at large-size sapphire crystal growth by different crystal growth methods such as KY, EFG, HEM, Cz and TGT.

2. Sapphire crystal research center has strong interests on the experimental challenges of largesize sapphire crystal, led by Prof. Jun Xu from Shanghai Institute of Ceramics, CAS.

3. Experiences in large-size sapphire crystal growth, annealing, detection, cutting and grounding, as well as the home made facilities.

To provide manpower for crystal growth experiments and management to meet the optics requirements of

KAGRA (LCGT) .

Permanent members (16 now)• Jun Xu (Shanghai Institute of Ceramics, CAS) Leader of SIC-KAGRA (LCGT) Collaboration

Experimental: Experimental: • Growth Parameters (6)----To optimize the growth parameters and verify the

lab designed facility and thermal simulation.• Cutting & Grounding (3)

II. Center ActivitiesII. Center Activities

Thermal Heater Design (2):----crucial for obtaining high quality crystal. To obtain homogeneous temperature gradient with improved heater and rectangular shielding set-up.

Furnace components, Mechanics, Vacuum and system heater (2):----Furnace components: attain high temperature and high vacuum.

Permanent members (16 now)II. Center ActivitiesII. Center Activities

Thermal Simulation: Temperature distribution mode (WT50)

WT50 modelWT50 limited gridding

(2810 units, 1467modes)

WT50 simulation results for thermal field distribution

Thermal Simulation (2):II. Center ActivitiesII. Center Activities

– Memorandum on Academic Exchange between the Institute for Cosmic Ray Research, the University of Tokyo & the Sapphire R&D Center, the Shanghai Institute of Ceramics, CAS has been signed up by Jun Xu & Takaaki Kajita on January 8th , 2012.

IIA. MemorandumIIA. Memorandum

IIB. First Samples sent for IIB. First Samples sent for Absorption Measurement in Absorption Measurement in

KAGRAKAGRA

III Proposed Works:III Proposed Works:Progress of Sapphire Crystal Growth

1890 1970 1980 1990 2000 20111890 1970 1980 1990 2000 2011

Abrd

China

Verneuil10-20mmt

CZ 100mmt

HEM 125mmt

KY220mm

HEM340mmt

65KG

KY300mmt

65KG

VGF80mmt

TGT120mmt 8KG

CZ200mmt

2008KY350mmt 65KG

2006KY260mmt30K

G

2011KY400mmt

85KG

Sapphire crystal grown by VGFSapphire crystal grown by VGF

TGT: self-possessed initial TGT: self-possessed initial technologytechnology

1. molybdenum crucible2. seed crystal groove is set at the bottom of the

crucible to prevent the seed crystal from melting3. temperature field was supplied by the graphite

heater and the cooling apparatus.4. Heater cylinder is cut into the shape of

rectangular crate and fastened on the graphite electrode plate connecting to the water cooled electrode bar.

5. TGT with Graphite Heater produced crystals with rose pink and annealing was required.

118m

m

97m

m

89m

m

69m

m

149m

m

Dia.114mm

TGT: self-possessed initial TGT: self-possessed initial technologytechnology

Sapphire grown by HEMSapphire grown by HEM

By adjusting the By adjusting the Helium gas flow Helium gas flow rate rate and and heater power heater power to control the to control the temperature gradient, the crystal is temperature gradient, the crystal is formed slowly formed slowly from bottom to top from bottom to top by exploiting the heat exchanger by exploiting the heat exchanger Helium to bring away the heat and Helium to bring away the heat and forming the vertical temperature forming the vertical temperature gradient in the crystal growth zone.gradient in the crystal growth zone.

Sapphire grown by HEM: XRC & Sapphire grown by HEM: XRC & dislocation densitydislocation density

y=y0 + (A/(w*sqrt(PI/2)))*exp(-2*((x-xc)/w)^2)

Sapphire crystal grown by CZ Sapphire crystal grown by CZ methodmethod

1. Easy to view the crystal growth process.2. Exploit the seed crystal with specific orientation and apply the neck

shrunken techniques to obtain high optical quality crystal with faster growth rate and higher integrity.

3. Defect caused by the uncontrolled complex liquid activity produced by the combined actions of forced convection induced by the rotation of crystal and crucible, together with the free convection arisen by the gravitation.

4. During large crystal growth process, defects are caused by mechanical perturbation

Sapphire grown by CZ method: Sapphire grown by CZ method: dislocation density & XRCdislocation density & XRC

Sapphire grown by CZ method under Sapphire grown by CZ method under polarized light: mosaic structure & polarized light: mosaic structure & large large boundaryboundary

Crystal defects such as mosaic structure and low-angle boundary under stress gauge.

Principle of KY methodPrinciple of KY method1. a cold seed crystal is lowered to

touch the melted raw material2. crystal is started to grow when the

interface temperature is lower than the melting point

3. lift the crystal stage by stage slowly to enlarge the exposed surface.

4. crystal was kept clear of the crucible wall during the growth process and at the end of growth the inside stress would be greatly reduced.

5. However, comparatively large heat thermal shock was produced when crystal departing from the remaining fused mass.

Sapphire crystal grown by KY Sapphire crystal grown by KY methodmethod

Sapphire obtained by KY: dislocation Sapphire obtained by KY: dislocation density & XRCdensity & XRC

FWHM (Full Wave at Half Maximum) for the samples at the center with 11.484’’, edge site 1 with 12.276’’ and edge site 2 with 16.992’’ show that the sample with higher crystal quality possessing lower dislocation density.

Comparison of different crystal growth Comparison of different crystal growth methodmethod• Venuil, Cz, Float Zone methodVenuil, Cz, Float Zone method: Crystal quality and size are

both limited which can hardly meet the high requirements of optical application.

• HEM, TGTHEM, TGT: Large sized sapphire crystal with good quality can be obtained where HEM requiring plenty of Helium as cooling carrier and TGT with Graphite Heater producing crystal with rose pink.

• TGT, KYTGT, KY: Post Treatment such as high temperature annealing is required although it’s complex and with high cost. The optical quality of KY crystals are improved after in-site annealing.

TechnologyTechnology Dislocation Dislocation DensityDensity

(Pits/cm(Pits/cm22))

FWHMFWHM(″(″ ）） Purity Purity

(%)(%)Impurity Impurity

ContenContent (ppm)t (ppm)

KYKY(Kyropoulos)(Kyropoulos)

101022-10-1033 <20<20 99.9999.9966

﹤﹤11

HEMHEM(Heat Exchange (Heat Exchange

Method)Method)

101033-10-1044

>15>15 99.9999.99

77

CZCZ(Czochralski )(Czochralski )

﹥﹥101033 >20>20 99.9999.9900

﹤﹤44

TGTTGT ﹥﹥101033 >15>15

Comparison of sapphire crystalComparison of sapphire crystal

IV. Facilities

IV. Facilities

IV. Facilities

single side groundingsurface finish testing instrumentchamfering machineAutomatic chip mounter

annealing furnace

Spheronizatorroughness measuring apparatusoptical microscopeatomic microscopeflatness inspective meter

IV. Facilities--Cutting and Grounding for Large Sized Sapphire Cutting and Grounding for Large Sized Sapphire

CrystalCrystal

V Human Resources

SummarySummary• We will provide significant manpower and We will provide significant manpower and

sapphire crystal resources for KAGRA sapphire crystal resources for KAGRA (LCGT) experiments.(LCGT) experiments.

• Permanent Members = 16Permanent Members = 16

• We are willing to expand our participation We are willing to expand our participation to wider area. Any suggestions are to wider area. Any suggestions are welcome.welcome.

Thank you for your attention!xujun@mail.shcnc.ac.cn; 13501650580

Factors that may affect Absorption ParametersFactors that may affect Absorption Parameters

1. Impurity2. Dislocation Density3. Micro-defects: Large boundary4. Micro-defects: Low angle boundary Adjusted by growth parameters and growth

method; Defects in the crystals obtained by different growth method results in different emphasizes.

• 60kg: dia240-260 mm: 350 mm thickness• 80kg: dia260-280 mm: 400 mm thickness